Field of the Invention
The present invention relates generally to apparatus for cleaning electrical contacts, and more particularly to tools for conveniently cleaning electrical jacks such as the 1/4 inch TRS and the Bantam (TT) patch jacks found in recording and broadcast equipment without requiring the disassembly of the equipment, and without resulting in contaminants being left in the equipment, which contaminants could cause shorting of the equipment.
Recording and broadcast facilities typically utilize a large number of discrete electrical and electronic components permanently mounted in racks or consoles and called, collectively, a patch bay. These components are interconnected with patch cords as needed for the particular purpose for which the facility is being used. The patch cords, which have electrical plugs at both ends, are plugged into jacks in the patch bay, which jacks are the inputs and outputs of the various components contained in the patch bay.
It may thereby be appreciated that electrical signal flow may be routed through selected components in the patch bay by inserting the patch cords between the selected components to conveniently and quickly create a customized recording or broadcast circuit for a particular recording session or broadcast. This process is analgous to the operation of an old-fashioned telephone switchboard, where an operator made connections by patching a calling party's line to the desired receiving party's line via a patch cord.
The patch jacks contained in the patch bay are typically mounted in rows of approximately 24 across on a 19 inch wide rack, with the jacks being hard wired to the various electrical and electronic components. Since each patch jack typically has five signal routing wires coming from the jack and going to the input or the output of a component, it may be appreciated that the interior of a patch bay is quite congested with the various wires. The density of the wiring connected to the patch jacks therefore makes them relatively inaccessible, except from the front where a patch cord plug may be plugged in.
Since patch bay apparatus has an extended life, a problem that has arisen is that of surface deterioration of the electrical contacts of the patch jacks contained in the patch bay. Unlike the patch cord plugs, which may easily be cleaned, the jacks are inaccessible due to the wiring density and to their design. Patch bay jacks typically have three contacts which physically touch the patch cord plug to make electrical connections. One of these three contacts is a cylindrical barrel contact. In addition, when the patch cord plug is inserted, two pairs of normally closed breaking contacts are opened. The various contacts are placed on five contact arms extending from a jack mounting block.
Normal exposure of the patch bay jacks to the ambient atmosphere will cause corrosion over time. In addition, it is likely that spills may occur which will leave contaminants on the jack contacts, inhibiting good electrical contact. Other undesireable elements may also find their way into the patch bay, and it is therefore apparent that the periodic cleaning of the patch bay jacks is a requirement of normal equipment maintenance.
Known techniques for cleaning electrical contacts generally use an abrasive material mounted on a surface rubbed against the contact. Specifically, U.S. Pat. No. 2,503,299 to Rodriquez, U.S. Pat. No. 2,734,320 to Hoye, and U.S. Pat. No. 4,263,692 to Gremillion illustrate various types of devices using abrasive materials. The use of such approaches for cleaning patch bay jack contacts is impractical for several reasons.
First, it would be difficult to mount abrasive material on the irregular contour of a patch cord plug. Abrasive material wearing off during the cleaning operation may have serious effects of the electronic equipment contained in a patch bay. The references mentioned above are useful for removing fairly heavy corrosion from solid posts or heavy contacts, but are simply too brute force a technique for the sensitive electrical contacts of patch bay jacks. Finally, such an approach would be totally ineffective to clean the breaking contacts of a patch bay jack, which breaking contacts are not physically touched by the patch cord plug.
Two techniques have been used to clean patch bay jacks with a degree of success. The first of these is the use of a segment of steel in the shape of a patch plug but slightly oversize, with a slot cut through a diameter of the segment. The slot is compressed slightly when the segment is inserted into the jack, producing a knife edge effect cleaning action. This tool cleans two of the three contacts touching the plug, leaving the cylindrical barrel contact and the two pairs of breaking contacts untouched.
The other technique involves the use of a brush similar to a gun cleaning brush, which is inserted into the jack. While this is effective to clean the cylindrical barrel contact, it also does not clean the two pairs of breaking contacts. In addition, some metal bristles of the cleaning brush may fall out, causing shorts within the patch bay. This problem makes the use of such a brush quite undesirable.
It may therefore be appreciated that it is desireable to have an inproved tool or tools for cleaning the contacts of a patch bay jack. It is essential that the tool or tools be useable from the front of the patch bay, without requiring any disassembly. All of the contacts must be cleanable from this location, including the hard-to-reach breaking contacts. The technique should be as quick, easy, and convenient as possible, and further the tool or tools should be relatively inexpensive.